EP0283764A1 - Alkenylphenol and alkenylphenolether copolymers - Google Patents

Abstract

The invention relates to new alkenylphenol copolymers and their ethers. The copolymers according to the invention are alkenylphenol or alkenylphenol ether-alkenylsilane copolymers of the general formula: <IMAGE> photoresists

Description

The invention relates to new alkenylphenol copolymers or their ethers, namely copolymers of alkenylphenols or alkenylphenol ethers and alkenylsilanes.

worin m + n = 1 ist, p und r jeweils 0, 1 oder 2 bedeuten (und zwar unabhängig voneinander),
und für die Reste X, Y, R¹, R² und R³ folgendes gilt:
X = H, CH₃, C₂H₅ oder Halogen (d.h. F, Cl, Br, J),
Y = H, CH₃ oder Halogen,
R¹ = H, Halogen, Alkyl (d.h. CH₃ und C₂H₅) oder Halogenalkyl,
R² = H, CH₃, C₂H₅, C₃H₇ oder C₆H₅,
R³ = H oder R*,
wobei R* folgende Bedeutung hat:
CH₃, C₂H₅, C₃H₇, CH(CH₃)₂, C(CH₃)₃, C₆H₁₁, C₆H₅, CH₂C₆H₅, CH₂OCH₃, CH₂OCH₂CH₂OCH₃, Si(CH₃)₃ und Si(CH₃)₂C(CH₃)₃,
und wobei die Reste X, R¹ und R² jeweils gleich oder verschie­den sein können.The new inventions are alkenylphenol-alkenylsilane copolymers or their ethers of the general formula

where m + n = 1, p and r each represent 0, 1 or 2 (and independently of one another),
and the following applies to the radicals X, Y, R¹, R² and R³:
X = H, CH₃, C₂H₅ or halogen (ie F, Cl, Br, J),
Y = H, CH₃ or halogen,
R¹ = H, halogen, alkyl (ie CH₃ and C₂H₅) or haloalkyl,
R² = H, CH₃, C₂H₅, C₃H₇ or C₆H₅,
R³ = H or R *,
where R * has the following meaning:
CH₃, C₂H₅, C₃H₇, CH (CH₃) ₂, C (CH₃) ₃, C₆H₁₁, C₆H₅, CH₂C₆H₅, CH₂OCH₃, CH₂OCH₂CH₂OCH₃, Si (CH₃) ₃ and Si (CH₃) ₂C (CH₃) ₃,
and where X, R¹ and R² may each be the same or different.

In the above formula, m and n indicate the composition of the copolymers as molar fraction (mole fraction). The proportion of component m, i.e. of the alkenylphenol (ether) basic building block is approximately in the range between 0.99 and 0.01.

worin m + n = 1 ist, und X, R¹, R² und R³ die vorstehend ange­gebene Bedeutung haben.In particular, the invention relates to vinylphenol-vinylsilane copolymers or their ethers of the general formula

where m + n = 1 and X, R¹, R² and R³ have the meaning given above.

Preferred compounds are copolymers of vinylphenol, in particular p-vinylphenol, and vinyltrimethylsilane. Other compounds are, for example, copolymers with vinyltriethylsilane, vinyldiethylmethylsilane, vinyldimethylethylsilane, vinyldimethylphenylsilane, allyltrimethylsilane, allyltriethylsilane, allyldiethylmethylsilane, allyldimethylethylsilane and allyldimethylphenylsilane.

The new vinyl compounds are produced by ionic copolymerization of vinyl phenol ethers with non-hydrolyzable vinyl silanes; the corresponding vinylphenol copolymers result from cleavage of the ether groups. In ether cleavage, hydroxyl groups (-OH) are formed from the ether groups (-OR *).

For the copolymerization as vinylphenol ether, the o-, m- or p-isomers of methoxystyrene, ethoxystyrene, prop are preferred oxystyrene, isopropoxystyrene, t-butoxystyrene, phenoxystyrene and benzyloxystyrene are used. In the case of vinyl compounds, the copolymerization itself is generally carried out using known ionic initiators, preferably using anionic initiators. Examples of such initiators are butyllithium and naphthalene potassium. The proportion of the vinylsilane unit in the copolymer can be controlled in a targeted manner in anionic polymerization by varying the reaction parameters, such as the molar ratio of the monomers, solvent and initiator.

The copolymerization can also be carried out by free radicals; in the case of allyl (p and / or r = 1) and butenyl compounds (p and / or r = 2) it is preferably carried out in this way. Radical formers such as azoisobutyronitrile and peroxides are used for initiation. In the case of radical copolymerization, copolymers with a small proportion (<10 mol%) of vinylsilane monomer are obtained with vinylsilanes.

The copolymerization is generally carried out in non-polar aprotic organic solvents, especially in aliphatic or aromatic solvents such as heptane and toluene. The reaction temperature can range between -100 and + 100 ° C. The implementation proceeds in good yields. The yield can be increased to 100% if catalytic amounts of an ether or a tertiary amine are added during the copolymerization of the initiator solution; the product properties remain unchanged. Examples of such initiator mixtures are:
- n-butyllithium in heptane with the addition of tetrahydrofuran (molar ratio of n-BuLi: THF = 1: 1);
- n-Butyllithium in hexane with the addition of tetramethylethylenediamine (molar ratio 1: 1).

The ether groups are also cleaved in the aprotic medium. Lewis acids such as boron are used for ether cleavage tribromide. The hydroxyl groups formed during the cleavage process give the copolymers according to the invention an alkali solubility. To protect the hydroxyl groups during the polymerization, however, not only ether groups are suitable, but generally those groups which are stable under the respective polymerization conditions and can be split off again after the copolymerization. In addition to ether groups, these are, for example, ester groups (see: TW Greene, "Protective Groups in Organic Synthesis", John Wiley & Sons, New York, 1981, pages 87 to 113 and pages 152 to 192).

The vinylphenol-vinylsilane copolymers according to the invention are notable for good solubility in various organic solvents, such as alcohols, ketones and esters. These copolymers also have a high softening temperature and good film-forming properties. Because of the etch resistance in oxygen plasma, the compatibility with photoreactive components or solution inhibitors and the good alkali solubility, the copolymers according to the invention are particularly suitable as a base polymer for dry etch-resistant, high-resolution resists for UV, DUV (Deep UV), electron and X-rays. Resists of this type are the subject of the simultaneously filed European patent application No. ............ (VPA 87 P 3072 E), "Process for producing resist structures".

The invention will be explained in more detail using examples.

example 1

Opened in a carefully dried two-neck glass flask set gas inlet tube are freed from inhibitors in succession under dry, oxygen-free inert gas stream, for example nitrogen, 26.8 g (200 mmol) of p-methoxystyrene distilled over CaH₂, 10 g (100 mmol) of freshly distilled vinyltrimethylsilane, 34 ml of absolute toluene and 1.1 g (17 mmol) of n-butyllithium (in hexane) are added with stirring, and the flask is then immediately closed with a check valve filled with paraffin oil. The flask is then placed in a thermostat at 25 ° C. After 20 h, the polymerization is stopped by adding 1 to 2 ml of methanol, the reaction solution is added to a dropping funnel and slowly added dropwise to ten times the volume of methanol with vigorous stirring. The reaction product which precipitates as a white, fluffy mass is filtered off and dried to constant weight at 50 ° C. in a vacuum drying cabinet; Yield: 16.56 g (45% of theory). The copolymer obtained in this way consists of 58 mol% of methoxystyrene and 42 mol% of vinyltrimethylsilane basic building blocks.

10 g of the copolymer prepared in the manner described above are dissolved in 150 ml of dry dichloromethane in a dry three-necked round-bottom flask equipped with an internal thermometer, stirrer and cooler with a drying tube and cooled to about -80 ° C. in a cold bath. Thereafter, a solution of 16.2 g of boron tribromide in 50 ml of dry dichloromethane, likewise cooled to -80 ° C., is slowly added and the reaction solution is allowed to warm to room temperature with stirring within three hours. The solution turns red-brown. It is then mixed with about 5 ml of water and stirred vigorously, forming a sticky mass floating on the surface of the liquid. After adding 100 ml of 10% sodium hydroxide solution, the sticky mass dissolves in the aqueous alkaline phase. The organic phase is separated from the NaOH phase in a separating funnel and washed 2 to 3 times with NaOH. The combined NaOH extracts are acidified with hydrochloric acid and dissolved in ethyl acetate taken, washed with distilled water, dried over sodium sulfate and precipitated with a tenfold amount of petroleum ether. The product obtained is dried in a vacuum drying cabinet at 50 ° C. to constant weight; Yield: 7.07 g (76% of theory).

The copolymer obtained from p-vinylphenol and vinyltrimethylsilane is soluble in cyclohexanone and 2-ethoxyethyl acetate in addition to sodium hydroxide solution and ethyl acetate. The osmometrically determined molecular weight is 2400, the uniformity determined by gel permeation chromatography is 1.2. The copolymer softens (in a heated microscope) at approx. 155 ° C. The NMR spectrum shows that the ether cleavage was quantitative.

Example 2

According to Example 1, 26.8 g (200 mmol) of inhibitors, p-methoxystyrene distilled over CaH₂, 20 g (200 mmol) of freshly distilled vinyltrimethylsilane, 44 ml of absolute heptane and 1.4 g (22 mmol) are successively removed in a flask. n-Butyllithium (in the form of a 1.6 molar solution in hexane) and polymerized in the manner given there at 25 ° C. After 6 hours, the polymerization is terminated by adding 2 ml of methanol, then the reaction solution is placed in a dropping funnel and slowly dripped into ten times the volume of methanol with vigorous stirring. The resulting reaction product is filtered off and dried to constant weight at 50 ° C. in a vacuum drying cabinet; Yield: 15 g (32% of theory). The copolymer obtained in this way contains 45 mol% methoxystyrene and 55 mol% vinyltrimethylsilane.

The subsequent ether cleavage is carried out in accordance with Example 1. 1 to 1.3 moles of boron tribromide are used per mole of methoxystyrene. The yield is 84% of theory based on the isolated amount of copolymer of p-vinylphenol and vinyltrimethylsilane. The NMR spectrum shows that the ether cleavage was quantitative. The copolymer has a molecular weight of 5000 (determined by osmometry) and is soluble in sodium hydroxide solution (2n), 2-ethoxyethyl acetate and cyclohexanone. No softening is found under the heated microscope up to 200 ° C.

Example 3

According to Example 1, 13.4 g (100 mmol) of inhibitors, p-methoxystyrene distilled over CaH₂, 10 g (100 mmol) of freshly distilled vinyltrimethylsilane, 22 ml of absolute tetrahydrofuran and 0.7 g (11 mmol) are successively removed in a flask. n-Butyllithium (in the form of a 1.6 molar solution in hexane) and polymerized in the manner given there at 25 ° C. After 6 hours, the polymerization is stopped by adding 1 ml of methanol, then the reaction solution is placed in a dropping funnel and slowly added dropwise to ten times the volume of methanol with vigorous stirring. The flocculent reaction product is filtered off, washed with methanol and dried to constant weight in a vacuum drying cabinet at 50 ° C .; Yield: 5.6 g (24% of theory). The copolymer obtained in this way consists of 85 mol% of methoxystyrene and 15 mol% of vinyl trimethylsilane.

The subsequent ether cleavage is carried out in accordance with Example 1. The yield is 75% of theory, based on the amount of copolymer isolated. The copolymer of p-vinylphenol and vinyltrimethylsilane is soluble in sodium hydroxide solution (2n), cyclohexanone and 2-ethoxyethylacetate, the osmometric molecular weight is 1400. The NMR spectrum shows that the ether cleavage was quantitative.

Example 4

According to Example 1, 5.7 g (43 mmol) of inhibitors, p-methoxystyrene distilled over CaH₂, 4.3 g (43 mmol) of freshly distilled vinyltrimethylsilane and 22 ml of absolute tetrahydrofuran are added to a flask in succession. The sealed flask is then placed in a thermostat at a temperature of -60 ° C. After 1 h, when the internal temperature of the flask has reached -60 ° C., 0.14 g (0.86 mmol) of naphthalene potassium are added with stirring. After 16 hours, the polymerization is terminated by adding 1 ml of methanol, the reaction solution is added to a dropping funnel and slowly dripped into ten times the volume of methanol with vigorous stirring. The flocculent reaction product is filtered off, washed with methanol and dried to constant weight in a vacuum drying cabinet at 50 ° C .; Yield: 6.4 g (64% of theory). The copolymer obtained consists of 79 mol% of methoxystyrene and 21 mol% of vinyltrimethylsilane basic building blocks.

The subsequent ether cleavage is carried out in accordance with Example 1. The yield is 85% of theory, based on the amount of copolymer isolated. The copolymer of p-vinylphenol and vinyltrimethylsilane is soluble in sodium hydroxide solution (2n), cyclohexanone and 2-ethoxyethyl acetate.

Example 5

According to Example 1, 138 g (1.03 mol) of inhibitors, p-methoxystyrene distilled over CaH₂, 77 g (0.77 mol) of freshly distilled vinyltrimethylsilane and 280 ml of absolute toluene are added to a flask in succession. The sealed flask is then placed in a thermostat at 0 ° C. After 1 h, 11.5 g (0.18 mol) of n-butyllithium (in hexane) are added with stirring. After 70 h the polymerization was terminated by adding 10 ml of methanol, the reaction solution was placed in a dropping funnel and slowly dripped into ten times the volume of methanol with vigorous stirring. The reaction product which precipitates as a white, sticky mass is filtered off and dried to constant weight at 50 ° C. in a vacuum drying cabinet; Yield: 176 g (82% of theory). The copolymer obtained in this way consists of 54 mol% methoxystyrene and 46 mol% vinyltrimethylsilane basic building blocks.

In a three-necked round bottom flask (see Example 1) 160 g of the copolymer prepared in the manner described above are dissolved in 2 l of dry dichloromethane under inert gas and cooled to about -60 ° C. in a cold bath. Then an uncooled solution of 240 g of boron tribromide in 200 ml of dry dichloromethane is slowly added and the reaction solution is allowed to warm to room temperature over the course of three hours with stirring. The solution turns yellowish. It is then mixed with about 90 ml of water and stirred vigorously, forming a sticky mass floating on the surface of the liquid. After adding 2 l of 10% sodium hydroxide solution, the sticky mass dissolves in the aqueous alkaline phase. The organic phase is separated from the NaOH phase in a separating funnel and washed 2 to 3 times with NaOH. The combined NaOH extracts are acidified with hydrochloric acid, taken up in ethyl acetate, washed with distilled water, dried over sodium sulfate and precipitated with a tenfold amount of petroleum ether. The product obtained is dried in a vacuum drying cabinet at 50 ° C. to constant weight; Yield: 129 g (86% of theory).

The copolymer obtained from p-vinylphenol and vinyltrimethylsilane is soluble in cyclohexanone and 2-ethoxyethyl acetate in addition to sodium hydroxide solution and ethyl acetate. The molecular weight determined by osmometry is 2600, that by gel permeate tion chromatography determined uniformity 1.2. The copolymer softens (in a heated microscope) at approx. 155 ° C. The NMR spectrum shows that the ether cleavage was quantitative.

Claims (3)

1. Alkenylphenol and alkenylphenol ether-alkenylsilane copolymers of the general formula

where m + n = 1, p and r each represent 0, 1 or 2 (and independently of one another),
and the following applies to the radicals X, Y, R¹, R² and R³:
X = H, CH₃, C₂H₅ or halogen (ie F, Cl, Br, J),
Y = H, CH₃ or halogen,
R¹ = H, halogen, alkyl (ie CH₃ and C₂H₅) or haloalkyl,
R² = H, CH₃, C₂H₅, C₃H₇ or C₆H₅,
R³ = H or R *,
where R * has the following meaning:
CH₃, C₂H₅, C₃H₇, CH (CH₃) ₂, C (CH₃) ₃, C₆H₁₁, C₆H₅, CH₂C₆H₅, CH₂OCH₃, CH₂OCH₂CH₂OCH₃, Si (CH₃) ₃ and Si (CH₃) ₂C (CH₃) ₃,
and where X, R¹ and R² may each be the same or different. 2. Vinylphenol and vinylphenol ether-vinylsilane copolymers of the general formula

wherein m + n = 1 and X, R¹, R² and R³ are as defined in claim 1. 3. Vinylphenol-vinyltrimethylsilane copolymer.